In U.S. patent application Ser. No. 207,394, filed Nov. 17, 1980, now abandoned, there is disclosed a fiber feeding apparatus, commonly called a chute feed, for collecting and densifying fiber to be fed as a batt to a carding machine and the like. As described in greater detail in such application, the vertically extending wall forming the chute of the apparatus is perforated at its upper end, and a blower is utilized to create an air circulation path that flows from the discharge of the blower, around the upper end of the opening roller in the chute feed and generally tangentially therefrom, and then through the perforated wall portion and back to the inlet of the blower in a closed circuit. This arrangement offers the advantages of imposing a leveling influence on the fiber collecting in the vertical chute, and of keeping the lint and fiber dust within the chute feed by virtue of the closed air circulation path so as to avoid the necessity of having to filter the air, all as set forth in the foregoing application.
While the above-described chute feed offers significant advantages in some textile processing systems, there are other systems where it is important to remove the fiber lint, dust, or micro-dust altogether from the fiber batt formed by the chute feed. For example, in open end spinning applications, it is particularly advantageous to have the batt made essentially free of lint, dust and particularly micro-dust.
It is, of course, well known in the art to provide chute feeds which use an induced air flow to transport entrained fiber tufts to the vertical chute and to compress the fiber collected therein, typical examples of such chute feeds being disclosed in U.S. Pat. Nos. 3,482,883 and 4,219,289. It is also known to provide air delivery systems for fiber tufts which include some arrangement for exhausting the air through any convenient vacuum source, such as the existing extractor found on carding machines which are fed by the chute feeds. Thus, in U.S. Pat. No. 4,136,911, air from a blower is forced down through the vertical column of collected fiber in the chute feed and removed through an apertured wall near the bottom of the column which is connected to the card extractor. In U.S. Pat. No. 4,176,988, air with fiber entrained therein is removed through a perforated wall of the vertical chute and exhausted by any suitable vacuum source.
Where air is used to deliver fiber to the chute feed and/or compress fiber in the chute feed by being forced downwardly through a substantially vertical column of fiber, variations in the pressure or flow of such air do not appear to be particularly significant since the delivery of, or compression of, the fiber will not be substantially affected by such variations. Thus, where the air is exhausted by using the vacuum source available from the card extractor, it is known that the vacuum offered by the card extractor will vary, depending on the load that is imposed on the extractor at any given time, but this variation does not appear to adversely affect the fiber delivery and/or fiber compressing function of the air system. However, where the air system is utilized in a manner described in the aforesaid U.S. application Ser. No. 207,394 to causing leveling of the fiber by passing the air through perforations located adjacent the upper end of the vertical chute, it has been found that variations in the vacuum source used to exhaust the air will have an adverse effect on the ability of the air flow to level the fiber at the upper end of the vertical chute. Therefore, in accordance with the present invention, a chute feed is provided with a unique air flow arrangement which serves to separate the fiber from the opening roller, cause leveling of the fiber in the vertical chute, and then exhaust the air and any dust or micro-dust therein in a controlled pressure environment that does not adversely effect the fiber leveling function of the air flow.
Additionally, some chute feeds include an oscillating plate that forms one wall of the vertical chute, and this plate moves toward and away from an opposed fixed wall forming another wall of the vertical chute to thereby mechanically compress or densify the fiber in the vertical chute during movement of the oscillating plate in its compressind direction, typical examples of chute feeds having oscillating compression plates being disclosed in U.S. Pat. Nos. 3,896,523 and 3,728,759. While these oscillating plates have the obvious effect of compressing the fiber when the plate moves in a direction toward the fixed plate, the movement of the plate in the opposite direction has a tendency to permit the fiber between the plates to reexpand or open, thereby reducing, to at least some extent, the effectiveness of the mechanical compression of the fiber by the oscillating plate. Moreover, when the oscillating plate is used in combination with a fiber leveling system as disclosed in the aforesaid application Ser. No. 207,394, the movement of the oscillating plate in opposite directions will result in somewhat different pressure conditions in the compartment which is receiving air through the perforated plate, and this pressure difference can, at least to some extent, adversely effect the aforesaid controlled pressure environment that is desirable for maximum fiber leveling in the vertical chute. These drawbacks are overcome in the present invention, which not only isolates the oscillating plate from the air current used to cause leveling of the fiber so as to remove any tendency for the plate to affect the leveling air circulating system, but which also utilizes the movement of the plate in both directions to assist in compressing the fiber in the vertical chute.